Several energy executives are touting the potential of the Mississippi Lime formation in Oklahoma to turn into a major oil field. "If you think about all the potential extension, I've come up with about 20 million acres' potential," said Julie Garvin, president of Roxanna Oil. "Because of the vast acreage, it has given opportunities for a lot of companies of different sizes to participate," said Earl Reynolds, Chaparral Energy's chief operating officer and executive vice president.